Direct air contact liquid cooling system heat exchanger assembly

ABSTRACT

A heat exchanger assembly for use in hybrid liquid-air cooling system adapted to provide a liquid cooling mechanism for components in a personal computer system. The heat exchanger assembly consists of a heat exchanger chamber, though which the thermal transfer liquid flows. An air pump injects air bubbles into the heat exchanger chamber through a porous material. The air bubbles rise up through the thermal transfer liquid and exit at the top of the heat exchanger chamber through a semi-permeable membrane which inhibits loss of the thermal transfer fluid. As the air bubbles pass through the thermal transfer liquid, heat is exchanged directly between the thermal transfer liquid and the contained air. The heat is then removed from the system as the heated air is expelled from the heat exchanger chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of, and claims priority from, U.S. patent application Ser. No. 12/120,593 filed on May 14, 2008, which in turn is related to, and claims priority from, U.S. Provisional Patent Application Ser. No. 60/917,965 filed on May 15, 2007, both of which are herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention is related generally to cooling systems associated with component circuit boards such as those installed in expansion slots of personal computer systems, and specifically, to a hybrid liquid-to-air cooling system adapted for use in cooling integrated circuit components, such as graphics processing units, installed on a component circuit board.

Personal computer systems which are design for desktop or under-desk use, and which are typically characterized by a main-board or motherboard housed in a chassis or case, often provide one or more expansion slots into which auxiliary components may be installed. These auxiliary components may include network adapter circuit boards, modems, specialized adapters, and graphics display adapters. These auxiliary components may receive power through the connection to the motherboard, or through additional connections directly to a system power supply contained within the chassis or case. Additional components, such as hard drives, disk drives, media readers, etc. may further be contained within the chassis or case, and coupled to the system power supply and motherboard as needed.

During operation, the motherboard and various auxiliary components consume power and generate heat. To ensure proper functionality of the computer system, it is necessary to regulate the operating temperatures inside the environment of the chassis or case. Individual integrated circuits, especially memory modules and processors, may generate significant amounts of heat during operation, resulting in localized hot spots within the chassis environment. The term “processors”, as used herein, and as understood by one of ordinary skill in the art, describes a wide range of components, which may include dedicated graphics processing units, microprocessors, microcontrollers, digital signal processors, and general system processors such as those manufactured and sold by Intel and AMD. Failure to maintain adequate temperature control throughout the chassis environment, and at individual integrated circuits, can significantly degrade the system performance and may eventually lead to component failure.

Traditionally, one or more cooling fans are associated with the system power supply, to circulate air throughout the chassis environment, and to exchange the high temperature internal air with cooler external air. However, as personal computer systems include increasing numbers of individual components and integrated circuits, and applications become more demanding on additional processing components such as graphics display adapters, a system power supply cooling fan may be inadequate to maintain the necessary operating temperatures within the enclosed chassis environment.

Specialized liquid cooling systems are available for some components in a personal computer system. Specialized liquid cooling systems typically required a coolant circulation pathway through which a coolant or thermal transfer liquid, often driven by an impeller is circulated. The circulation pathway routes the thermal transfer liquid between a heat exchanger such as a radiator and a heat source, such as a CPU, GPU, microprocessor or transformer. Specialized liquid cooling systems are well adapted for maintaining adequate operating temperatures for individual components. However, these specialized liquid cooling systems are not easily adapted for use with a wide variety of components or adapter boards in a personal computer system, and are often bulky and noisy during operation.

Accordingly, it would be advantageous to provide a hybrid liquid-air cooling system which may be easily adapted to provide a compact and quiet liquid cooling mechanism for use with a wide range of components or adapter boards in a personal computer system, and which functions cooperatively with an air cooling system.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present disclosure provides a compact heat exchanger assembly for use with hybrid liquid-air cooling system which is generally adapted to provide a liquid cooling mechanism for use with a wide range of semiconductor components or adapter circuit boards installed in a personal computer system, and which functions cooperatively with an air cooling system. The heat exchanger assembly consists of a heat exchanger chamber, though which the thermal transfer liquid pass during circulation through the cooling system. As the thermal transfer liquid passes through the heat exchanger, an air pump injects air bubbles into the heat exchanger chamber through a porous material. The air bubbles rise up through the thermal transfer liquid and exit at the top of the heat exchanger chamber through a semi-permeable membrane which inhibits loss of the thermal transfer fluid. As the air bubbles pass through the thermal transfer liquid, heat is exchanged directly between the thermal transfer liquid and the contained air. The heat is then removed from the system as the heated air is expelled from the heat exchanger chamber. A valve assembly prevents the thermal transfer liquid from entering the air pump in the event air flow through the heat exchanger chamber is stopped.

The present disclosure further provides a method for removing heat from a thermal transfer liquid circulating within a liquid cooling system adapted for use with a wide range of semiconductor components or adapter circuit boards installed in a personal computer system. Heated thermal transfer liquid is circulated into a heat exchanger assembly, including a heat exchanger chamber. Lower temperature air is injected into the heat exchanger chamber through a porous material by a pump. Rising through the heated thermal transfer liquid within the heat exchanger chamber, the air bubbles absorb thermal energy from the thermal transfer liquid. Heated air is released from the heat exchanger chamber via a semi-permeable membrane at the top of the heat exchanger chamber and discharged into the external environment, removing thermal energy from the system. The cycle is repeated as the thermal transfer liquid is circulated between one or more heat sources and the heat exchanger chamber.

The foregoing features, and advantages set forth in the present disclosure as well as presently preferred embodiments will become more apparent from the reading of the following description in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification:

FIG. 1 is a fluid circuit diagram of the liquid cooling system heat exchanger assembly of the present disclosure; and

FIG. 2 is a fluid circuit diagram of an alternate embodiment heat exchanger of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. It is to be understood that the drawings are for illustrating the concepts set forth in the present disclosure and are not to scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description illustrates the invention by way of example and not by way of limitation. The description enables one skilled in the art to make and use the present disclosure, and describes several embodiments, adaptations, variations, alternatives, and uses of the present disclosure, including what is presently believed to be the best mode of carrying out the present disclosure.

Turning to FIG. 1, a liquid cooling system heat exchanger assembly 100 of the present disclosure, for use with electronic components such as those found in a personal computer consists generally of one or more cold plates 102 disposed in contact with heat sources 104, and an associated circulating liquid coolant flow pathway 106 within which flows a thermal transfer fluid 107. The liquid coolant flow pathway 106 includes a liquid pump 108 and/or fluid reservoir, and is operatively coupled to deliver a flow of heated thermal transfer fluid 107 to a direct air contact heat exchanger 110 for extracting absorbed heat from the thermal transfer fluid 107. Generally, the liquid coolant flow pathway 106 consists of one or more tubes or pipes, which contain the circulating thermal transfer fluid 107, and which are configured to provide a circulating flow pathway between each cold plate 102 and the heat exchanger 110.

During operation, the thermal transfer fluid 107 circulates through the coolant flow pathways 106, drawing heat away from the heat sources 104 through the associated cold plates 102, and dissipating the heat directly to air bubbles formed within the heat exchanger 110 for discharge out of the system as the thermal transfer fluid 107 flows through the direct air contact heat exchanger 110.

In an embodiment of the present invention, the direct air contact heat exchanger 110 is configured to facilitate a direct exchange of heat between the thermal transfer fluid 107 and lower temperature ambient air. The heat exchanger 110 consists of a vessel 200 defining a heat exchanger chamber 202, having at least one fluid flow inlet 204 and at least one fluid flow outlet 206. Thermal transfer fluid 107 circulating in the cooling system 106 is routed into the fluid flow inlet 204, and exits the heat exchanger chamber 202 through the fluid flow outlet 206. At the base 210 of heat exchanger chamber 202, an air insertion assembly 212 consists of a porous material 214 which permits forced entry of bubbles 216 of the ambient air. The ambient air is forced through the porous material 214 from an external air intake 218 by means of an air pump 220. A suitable backflow diverter or directional valve 222 prevents any thermal transfer fluid 107 which may pass through the porous material 214, from flowing back into the air pump 220 and draining from the system via the air intake 218.

While the present disclosure illustrates and describes the heat exchanger chamber 202 as having a base and a top, defined with respect to the direction of gravity, those of ordinary skill in the art will recognize that a variety of different configurations for the heat exchanger chamber 202 may be utilized which do not require the chamber 202 to be oriented with respect to gravity for proper operation, but which still enable the introduction and removal of ambient air bubbles 216 to a circulating flow of thermal transfer liquid 107.

As the ambient air bubbles 216 move through the thermal transfer fluid 107 in the heat exchanger chamber 202, the boundary surfaces between the thermal transfer fluid 107 and the ambient air bubbles 216 provides a large contact region and an optimal low thermal resistance contact between the fluid and the air, allowing thermal energy (heat) to transfer rapidly between the thermal transfer fluid 107 and the bubbles 216 of ambient air. As the air bubbles 216 exit the heat exchanger chamber 202, the released air removes the thermal energy (heat) from the cooling system.

As the air bubbles 216 rise through the thermal transfer fluid 107 in the heat exchanger chamber 202, they additionally absorb significant quantities of moisture from the thermal transfer fluid 107, often reaching near 100% humidity. In one embodiment, at the top of the heat exchanger chamber 202, a semi-permeable membrane 224 permits the bubbles 216 of air to exit the heat exchanger chamber 202 through an exhaust port or air outlet 226, while simultaneously preventing the absorbed thermal transfer fluid 107 from exiting out the exhaust port or air outlet 226.

In an alternate embodiment, shown in FIG. 2, the thermal transfer fluid does not completely fill the heat exchanger chamber 202, and the air bubbles 216 rising through the thermal transfer fluid 107 are contained at the top of the heat exchanger chamber 202, where a plurality of condensation fins 300 extend vertically downward from a top surface 302 of the heat exchanger chamber 202. Moisture 304 from the thermal transfer fluid 107 trapped in the rising bubbles 216 of air condenses onto the surfaces of the condensation fins 300, and drips back into the volume of thermal transfer fluid 107 within the heat exchanger chamber 202. The heated and dried air accumulated adjacent the top surface 302 of the heat exchanger chamber 202 then circulates out of the system through the air outlet 226.

Those of ordinary skill in the art will recognize that the specific shape and arrangement of the heat exchanger 202, inlets 204, outlets 206, exhaust ports 226, and ambient air entry ports 218 may be adapted to accommodate the particular application for which the cooling system is configured. For example, the heat exchanger chamber may be cylindrical in shape, axially aligned with the direction of gravity. The fluid flow inlet near may be positioned adjacent the base of the heat exchanger chamber, and the fluid flow outlet near the top, resulting in an upward flow of thermal transfer fluid through the heat exchanger chamber. The ambient air entry port may be centrally disposed in the base, and the top end of the cylindrical chamber may define the exhaust port, such that bubbles of ambient air injected into the heat exchanger chamber at the base travel upward through the flow of thermal transfer fluid, and exit at the top through the exhaust port.

As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 

1. A liquid cooling system adapted to provide a direct air contact liquid cooling mechanism, comprising: a pathway for circulating a flow of thermal transfer fluid between at least one heat source and a heat exchanger; and wherein said heat exchanger is configured to facilitate a direct transfer of heat from the thermal transfer fluid to air bubbles passing through the heat exchanger.
 2. The liquid cooling system of claim 1 wherein said heat exchanger includes a heat exchanger chamber having at least one inlet for receiving a flow of thermal transfer fluid, at least one outlet for discharging a flow of thermal transfer fluid, an air insertion assembly for receiving a supply of ambient air; and at least one air exhaust port for evacuating heated air which has passed through said flow of thermal transfer fluid within said heat exchanger chamber and absorbed thermal energy there from.
 3. The liquid cooling system of claim 2 wherein said air insertion assembly includes a porous material disposed between a source of ambient air and said heat exchanger chamber, said porous material generally permitting passage of said ambient air and generally preventing passage of said thermal transfer fluid; and an air pump configured to direct a flow of ambient air through said porous material into said heat exchanger chamber.
 4. The liquid cooling system of claim 3 wherein said air insertion assembly further includes a back flow valve configured to prevent a flow of thermal transfer fluid from exiting said heat exchanger chamber through said air pump.
 5. The liquid cooling system of claim 2 wherein said at least one exhaust port is separated from said heat exchanger chamber by a semi-permeable membrane, said semi-permeable membrane configured to pass a flow of air and to exclude a flow of thermal transfer fluid.
 6. The liquid cooling system of claim 2 wherein said heat exchanger chamber includes a plurality of moisture condensation fins extending from at least an upper inner surface of said heat exchanger chamber into a pocket of contained air disposed between said upper inner surface of said heat exchanger chamber and a volume of thermal transfer fluid contained within said heat exchanger chamber, said moisture condensation fins configured to facilitate the condensation of moisture from said entrapped air.
 7. The liquid cooling system of claim 1 wherein said pathway for circulating a flow of thermal transfer fluid and said heat exchanger are adapted for use in a personal computer system.
 8. The liquid cooling system of claim 1 wherein said pathway for circulating a flow of thermal transfer fluid is a closed loop pathway, and includes at least one means for imparting a flow to said thermal transfer fluid within said pathway. 